Similarly I would not suggest trying to stretch the tire with your hands and feet. Seems like a good way to kink the wire bead and that'll just produce problems. Sorry PNB, if it works for you then fine and maybe something was lost in the explanation but I wouldn't do it the way I think you're saying as it would certainly kink the wire.

However slightly filling the tube works superbly. Just enough to form a donut without growing. And then poke it into the tire and around into the center of the rim so it's not up where you can pinch it with the tire irons.

Finally the last thing. When you get the bead seated to where you're down to the last 10 or less inches that still needs to go in put some light pressure on the tire lever and with your other hand run your thumb or finger around the seated bead to push the bead wire down into the valley in the center of the rim. At that point you may want to let out the last of the air to make this easier. But getting the bead wire down into the valley is the key to making the tires super easy to mount. Repeat the finger pushing down as needed to keep it there. Also take small bites with the lever. If you try to force too much at once you're in for a fight.

So the two biggies are;

1)make sure the tube is around the rim and into the valley and not up over the edge of the rim where you can pinch it with the lever.

2)Repeatedly run your finger or thumb around the seated part to force the bead down into the valley of the rim channel.

And I'll echo Operator's comment about it being technique and not brute force. If it doesn't go decently easily then you're doing something wrong or not doing something that you should be doing.